asthma in the acute care setting

A M A N Y A B O U Z E I D M D , F R C P , F C C S

P R O F . O F P U L M O N O L O G Y

C A I R O U N I V E R S I T Y

Asthma in the acute care setting

Objectives

Definition of acute asthma.

Clinical assessment.

Level of severity.

Treatment of acute severe asthma.

Definition of asthma exacerbation

Asthmatic exacerbations are defined as episodes of

increased breathlessness, cough, wheezing, chest

tightness or some combination of these symptoms.

Exacerbations may have a progressive or abrupt

onset and are always related to decreases in

expiratory (and in severe cases also in inspiratory)

airflows that should be quantified objectively by lung

function measurements(PEF;FEV1).GINA 2013.

Epidemiology

Annual worldwide deaths from asthma have been

estimated at 250,000 people.

Fatalities appear to have been decreasing worldwide

over the past 15 years, even in the face of an

increasing prevalence of the disease

Drugs 2009; 69 (17): 2363-2391

Clinical features Clinical features can identify some patients with severe asthma,e.g. severe breathlessness, tachypnea, tachycardia, silent chest,cyanosis, accessory muscle use, altered consciousness orcollapse.None of these singly or together is specific. Their absence does notexclude a severe attack.

Initial assessment – the role of symptoms,

signs and measurements

British Guideline on the Management of Asthma revised Jan 2012


PEF or FEV1 Measurements of airway calibre improve recognition of severity and guide hospital or at home management decisions. PEF is more convenient and cheaper than FEV1. PEF as % previous best value or % predicted most useful






Pulse Oximetry Necessary to determine adequacy of oxygen therapy and need for arterial blood gas measurement. Aim of oxygen therapy is to maintain SpO2 92%






Pulse oximetry Necessary to determine adequacy of oxygen therapy and need for arterial blood gas measurement. Aim of oxygen therapy is to maintain SpO2 92%

Blood gases (ABG)

Necessary for patients with SpO2 <92% or other features of life threatening asthma







Blood gases (ABG)

Necessary for patients with SpO2 <92% or other features of life threatening asthma

Chest X-ray Not routinely recommended in patients in the absence of:• suspected pneumomediastinum or

pneumothorax• suspected consolidation• life threatening asthma

• failure to respond to treatment satisfactorily

• requirement for ventilation







Blood gases (ABG) Necessary for patients with SpO2 <92% or other features of life threatening asthma

Chest X-ray Not routinely recommended in patients in the absence of:

• suspected pneumomediastinum or pneumothorax

• suspected consolidation• life threatening asthma

• failure to respond to treatment satisfactorily

• requirement for ventilation

Systolic paradox Abandoned as an indicator of the severity of an attack




Levels of severity of

acute asthma exacerbations

Near fatal asthma Raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures





Life threatening asthma

Any one of the following in a patient with severe asthma:

• PEF <33% best orpredicted

• SpO2 <92%• PaO2 <8 kPa• normal PaCO2 (4.6-6.0 kPa)

• silent chest• cyanosis• feeble respiratory

effort• bradycardia

• dysrhythmia• hypotension• exhaustion• confusion• coma







• PEF <33% best orpredicted





Acute severe asthma

Any one of:

• PEF 33-50% best or predicted• respiratory rate 25/min• heart rate 110/min

• inability to complete sentences in one breath







• PEF <33% best or predicted

• SpO2 <92%• PaO2 <8 kPa• normal PaCO2 (4.6-60 kPa)




Acute severe asthma

Any one of:



Moderate asthma exacerbation

• Increasing symptoms• PEF >50-75% best or predicted

• No features of acute severe asthma







• PEF <33% best or predicted





Acute severe asthma

Any one of:



Moderate asthma exacerbation

• Increasing symptoms• PEF >50-75% best or predicted

• No features of acute severe asthma

Brittle asthma • Type 1: wide PEF variability (>40% diurnal variation for >50% ofthe time over a period >150 days) despite intense therapy

• Type 2: sudden severe attacks on a background of apparentlywell-controlled asthma


Patients at risk of developing

near fatal or fatal asthma

Severe asthma Adverse behavioural or

psychosocial features

and

Recognised by combination of:




and Adverse behavioural or

psychosocial features

Severe asthma

recognised by one or more of:

• previous near fatal asthma (previous ventilation or respiratory acidosis)

• previous asthma admission

• requiring 3 classes of asthma medication

• heavy use of ß2 agonist

• repeated attendances at A&E for asthma care

• brittle asthma





Severe asthma Adverse behavioural or psychosocial features

recognised by one or more of:• non-compliance with treatment or monitoring• failure to attend appointments• self-discharge from hospital• psychosis, depression, other psychiatric illness or deliberate

self-harm• current or recent major tranquilliser use• denial• alcohol or drug abuse• obesity• learning difficulties• employment problems• income problems• social isolation• childhood abuse• severe domestic, marital or legal stress

and



Lessons learnt from

studies of asthma deaths

Many deaths from asthma are preventable – 88-92% of

attacks requiring

hospitalisation develop over 6 hours

Factors include:

• inadequate objective monitoring

•failure to refer earlier for specialist advice

• inadequate treatment with steroids


If the patient did not respond

NIPPV should be considered in ICU and it is unlikely

it would replace intubation in this unstable patients

Oxygen

Many patients with acute severe asthma are

hypoxaemic.

Supplementary oxygen should be given urgently to

hypoxaemic patients, using a face mask, Venturi

mask or nasal cannulae with flow rates adjusted as

necessary to maintain SpO2 of 94-98%.

Hypercapnea indicates the development of near-fatal

asthma and the need for emergency

specialist/anaesthetic intervention.


β2-Adrenergic Receptor Agonists

In most cases inhaled β2 agonists given in high doses

act quickly to relieve bronchospasm with few side

effects1

SABAs potentially induce additional responses that

may be of benefit in asthma, such as:2

1. Decreased vascular permeability

2. Increased mucociliary clearance

3. Inhibition of release of mast cell mediators.

4. Oxgen driven neubliser : continuoustly given.

1-British Guideline on the Management of Asthma revised Jan 2012

2- Drugs 2009; 69 (17): 2363-2391

Corticosteroids

Corticosteroids are recommended for most patients in

the emergency department, especially:

Those who do not respond completely to initial SABA

therapy,

Those whose exacerbation develops even though they were

already taking oral corticosteroids

Those with previous exacerbations requiring oral

corticosteroids

Drugs 2009; 69 (17): 2363-2391

Steroids reduce mortality, relapses, subsequent

hospital admission and requirement for β2 agonist

therapy.

The earlier they are given in the acute attack the

better the outcome.

It is not known if inhaled steroids provide further

benefit in addition to systemic steroids.

Inhaled steroids should however be started, or

continued as soon as possible to commence the

chronic asthma management plan

Corticosteroids


Magnesium Sulfate

Studies report the safe use of nebulized magnesium

sulphate, in a dose of 135 mg-1152 mg, in

combination with β2 agonists, with a trend towards

benefit in hospital admission.

A single dose of IV magnesium sulphate is safe and

may improve lung function in patients with acute

severe asthma


Anticholinergics

Combining nebulized ipratropium bromide with a

nebulized β2 agonist produces significantly greater

bronchodilation than a β2 agonist alone, leading to a

faster recovery and shorter duration of admission.

Anticholinergic treatment is not necessary and may

not be beneficial in milder exacerbations of asthma

or after stabilization


Intravenous Aminophylline

In acute asthma, IV aminophylline is not likely to

result in any additional bronchodilation compared to

standard care with inhaled bronchodilators and

steroids.

Side effects such as arrhythmias and vomiting are

increased if IV aminophylline is used


Leukotriene Receptor Antagonists

There is insufficient evidence at present to make a

recommendation about the use of leukotriene

receptor antagonists in the management of acute

asthma


Antibiotics

When an infection precipitates an exacerbation of

asthma it is likely to be viral.

The role of bacterial infection has been

overestimated.

Routine prescription of antibiotics is not indicated for

acute asthma.


Heliox

The use of heliox, (helium/oxygen mixture in a ratio

of 80:20 or 70:30), either as a driving gas for

nebulizers, as a breathing gas, or for artificial

ventilation in adults with acute asthma is not

supported on the basis of present evidence.


Heliox

A systematic review of ten trials, including 544

patients with acute asthma, found no improvement in

pulmonary function or other outcomes in adults

treated with heliox, although the possibility of benefit

in patients with more severe obstruction exists.


asthma in the acute care setting

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